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Lousada MB, Edelkamp J, Lachnit T, Fehrholz M, Pastar I, Jimenez F, Erdmann H, Bosch TCG, Paus R. Spatial Distribution and Functional Impact of Human Scalp Hair Follicle Microbiota. J Invest Dermatol 2024; 144:1353-1367.e15. [PMID: 38070726 DOI: 10.1016/j.jid.2023.11.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 10/17/2023] [Accepted: 11/01/2023] [Indexed: 02/26/2024]
Abstract
Human hair follicles (HFs) constitute a unique microbiota habitat that differs substantially from the skin surface. Traditional HF sampling methods fail to eliminate skin microbiota contaminants or assess the HF microbiota incompletely, and microbiota functions in human HF physiology remain ill explored. Therefore, we used laser-capture microdissection, metagenomic shotgun sequencing, and FISH to characterize the human scalp HF microbiota in defined anatomical compartments. This revealed significant compartment-, tissue lineage-, and donor age-dependent variations in microbiota composition. Greatest abundance variations between HF compartments were observed for viruses, archaea, Staphylococcus epidermidis, Cutibacterium acnes, and Malassezia restricta, with the latter 2 being the most abundant viable HF colonizers (as tested by propidium monoazide assay) and, surprisingly, most abundant in the HF mesenchyme. Transfection of organ-cultured human scalp HFs with S. epidermidis-specific lytic bacteriophages ex vivo downregulated transcription of genes known to regulate HF growth and development, metabolism, and melanogenesis, suggesting that selected microbial products may modulate HF functions. Indeed, HF treatment with butyrate, a metabolite of S. epidermidis and other HF microbiota, delayed catagen and promoted autophagy, mitochondrial activity, and gp100 and dermcidin expression ex vivo. Thus, human HF microbiota show spatial variations in abundance and modulate the physiology of their host, which invites therapeutic targeting.
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Affiliation(s)
- Marta B Lousada
- Monasterium Laboratory, Münster, Germany; Zoological Institute, Christian Albrechts University in Kiel, Kiel, Germany
| | | | - Tim Lachnit
- Zoological Institute, Christian Albrechts University in Kiel, Kiel, Germany
| | | | - Irena Pastar
- Dr Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Francisco Jimenez
- Mediteknia Skin & Hair Lab, Las Palmas de Gran Canaria, Spain; Ciencias de la Salud, Universidad Fernando Pessoa Canarias, Las Palmas de Gran Canaria, Spain
| | | | - Thomas C G Bosch
- Zoological Institute, Christian Albrechts University in Kiel, Kiel, Germany
| | - Ralf Paus
- Monasterium Laboratory, Münster, Germany; Dr Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA; CUTANEON, Hamburg, Germany.
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Paus R, Sevilla A, Grichnik JM. Human Hair Graying Revisited: Principles, Misconceptions, and Key Research Frontiers. J Invest Dermatol 2024; 144:474-491. [PMID: 38099887 DOI: 10.1016/j.jid.2023.09.276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/09/2023] [Accepted: 09/12/2023] [Indexed: 02/25/2024]
Abstract
Hair graying holds psychosocial importance and serves as an excellent model for studying human pigmentation and aging in an accessible miniorgan. Current evidence suggests that graying results from an interindividually varying mixture of cumulative oxidative and DNA damage, excessive mTORC1 activity, melanocyte senescence, and inadequate production of pigmentation-promoting factors in the hair matrix. Various regulators modulate this process, including genetic factors (DNA repair defects and IRF4 sequence variation, peripheral clock genes, P-cadherin signaling, neuromediators, HGF, KIT ligand secretion, and autophagic flux. This leads to reduced MITF- and tyrosinase-controlled melanogenesis, defective melanosome transfer to precortical matrix keratinocytes, and eventual depletion of hair follicle (HF) pigmentary unit (HFPU) melanocytes and their local progenitors. Graying becomes irreversible only when bulge melanocyte stem cells are also depleted, occurring later in this process. Distinct pigmentary microenvironments are created as the HF cycles: early anagen is the most conducive phase for melanocytic reintegration and activation, and only during anagen can the phenotype of hair graying and repigmentation manifest, whereas the HFPU disassembles during catagen. The temporary reversibility of graying is highlighted by several drugs and hormones that induce repigmentation, indicating potential target pathways. We advise caution in directly applying mouse model concepts, define major open questions, and discuss future human antigraying strategies.
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Affiliation(s)
- Ralf Paus
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA; CUTANEON - Skin & Hair Innovations, Hamburg, Germany; Monasterium Laboratory, Münster, Germany.
| | - Alec Sevilla
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA; Department of Internal Medicine, Lakeland Regional Health, Lakeland, Florida, USA
| | - James M Grichnik
- Department of Dermatology & Cutaneous Surgery, University of South Florida, Tampa, Florida, USA
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Sevilla A, Chéret J, Lee W, Paus R. Concentration-dependent stimulation of melanin production as well as melanocyte and keratinocyte proliferation by melatonin in human eyelid epidermis. Exp Dermatol 2023; 32:684-693. [PMID: 36601673 DOI: 10.1111/exd.14740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 12/13/2022] [Accepted: 12/31/2022] [Indexed: 01/06/2023]
Abstract
It remains unclear how the multifunctional indoleamine neurohormone, melatonin, alters melanin production and melanocytes within intact human epidermis under physiologically relevant conditions. In the current pilot study, we aimed to clarify this in long-term organ-cultured, full-thickness human eyelid skin, selected for its clinically recognized sensitivity to pigmentation-modulatory hormones. Warthin-Starry histochemistry showed that 100 μM melatonin significantly increased epidermal melanin content and melanocyte dendricity after 6 days of organ culture, even though tyrosinase activity in situ was inhibited, as assessed by quantitative immunohistomorphometry. While the higher melatonin dose tested here (200 μM) did not change epidermal melanization, but again inhibited tyrosinase activity, it increased the number and proliferation of both gp100+ epidermal melanocytes and keratinocytes as well as protein expression of the premelanosomal marker, gp100, ex vivo. Contrary to most previous studies, these eyelid skin organ culture results suggest that long-term melatonin application exerts overall stimulatory, dose-dependent effects on the epidermal pigmentary unit within intact human skin, which appear surprisingly tyrosinase-independent. While these provocative preliminary findings require further work-up and independent confirmation, they encourage one to systematically explore whether prolonged melatonin therapy can (re-)stimulate melanogenesis and increase the pool/activity of epidermal melanocytes in hypopigmented skin lesions.
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Affiliation(s)
- Alec Sevilla
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Jérémy Chéret
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Wendy Lee
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine Miami, Miami, Florida, USA
| | - Ralf Paus
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA.,CUTANEON - Skin & Hair Innovations, Hamburg, Germany.,Monasterium Laboratory, Münster, Germany
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Senna MM, Peterson E, Jozic I, Chéret J, Paus R. Frontiers in Lichen Planopilaris and Frontal Fibrosing Alopecia Research: Pathobiology Progress and Translational Horizons. JID INNOVATIONS 2022; 2:100113. [PMID: 35521043 PMCID: PMC9062486 DOI: 10.1016/j.xjidi.2022.100113] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 01/21/2022] [Accepted: 01/26/2022] [Indexed: 01/06/2023] Open
Abstract
Lichen planopilaris (LPP) and frontal fibrosing alopecia (FFA) are primary, lymphocytic cicatricial hair loss disorders. These model epithelial stem cell (SC) diseases are thought to result from a CD8+ T-cell‒dominated immune attack on the hair follicle (HF) SC niche (bulge) after the latter has lost its immune privilege (IP) for as yet unknown reasons. This induces both apoptosis and pathological epithelial‒mesenchymal transition in epithelial SCs, thus depletes the bulge, causes fibrosis, and ultimately abrogates the HFs' capacity to regenerate. In this paper, we synthesize recent progress in LPP and FFA pathobiology research, integrate our limited current understanding of the roles that genetic, hormonal, environmental, and other factors may play, and define major open questions. We propose that LPP and FFA share a common initial pathobiology, which then bifurcates into two distinct clinical phenotypes, with macrophages possibly playing a key role in phenotype determination. As particularly promising translational research avenues toward direly needed progress in the management of these disfiguring, deeply distressful cicatricial alopecia variants, we advocate to focus on the development of bulge IP and epithelial SC protectants such as, for example, topically effective, HF‒penetrating and immunoinhibitory preparations that contain tacrolimus, peroxisome proliferator-activated receptor-γ, and/or CB1 agonists.
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Key Words
- 5ARI, 5α-reductase inhibitor
- AA, alopecia areata
- AGA, androgenetic alopecia
- CRH, corticotropin-releasing hormone
- EMT, epithelial‒mesenchymal transition
- FFA, frontal fibrosing alopecia
- HF, hair follicle
- IP, immune privilege
- K, keratin
- KC, keratinocyte
- LPP, lichen planopilaris
- MAC, macrophage
- MHC, major histocompatibility complex
- PCA, primary cicatricial alopecia
- PCP, personal care product
- PPAR-γ, peroxisome proliferator–activated receptor-γ
- SC, stem cell
- SP, substance P
- eHFSC, epithelial hair follicle stem cell
- α-MSH, α-melanocyte-stimulating hormone
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Affiliation(s)
- Maryanne Makredes Senna
- Department of Dermatology, Massachusetts General Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Erik Peterson
- Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Ivan Jozic
- Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Jérémy Chéret
- Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Ralf Paus
- Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, Miller School of Medicine, University of Miami, Miami, Florida, USA.,Monasterium Laboratory, Münster, Germany.,CUTANEON, Hamburg, Germany
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Wikramanayake TC, Chéret J, Sevilla A, Birch-Machin M, Paus R. Targeting mitochondria in dermatological therapy: Beyond oxidative damage and skin aging. Expert Opin Ther Targets 2022; 26:233-259. [PMID: 35249436 DOI: 10.1080/14728222.2022.2049756] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION The analysis of the role of the mitochondria in oxidative damage and skin aging is a significant aspect of dermatological research. Mitochondria generate most reactive oxygen species (ROS); however, excessive ROS are cytotoxic and DNA-damaging and promote (photo-)aging. ROS also possesses key physiological and regulatory functions and mitochondrial dysfunction is prominent in several skin diseases including skin cancers. Although many standard dermatotherapeutics modulate mitochondrial function, dermatological therapy rarely targets the mitochondria. Accordingly, there is a rationale for "mitochondrial dermatology"-based approaches to be applied to therapeutic research. AREAS COVERED This paper examines the functions of mitochondria in cutaneous physiology beyond energy (ATP) and ROS production. Keratinocyte differentiation and epidermal barrier maintenance, appendage morphogenesis and homeostasis, photoaging and skin cancer are considered. Based on related PubMed search results, the paper evaluates thyroid hormones, glucocorticoids, Vitamin D3 derivatives, retinoids, cannabinoid receptor agonists, PPARγ agonists, thyrotropin, and thyrotropin-releasing hormone as instructive lead compounds. Moreover, the mitochondrial protein MPZL3 as a promising new drug target for future "mitochondrial dermatology" is highlighted. EXPERT OPINION Future dermatological therapeutic research should have a mitochondrial medicine emphasis. Focusing on selected lead agents, protein targets, in silico drug design, and model diseases will fertilize a mito-centric approach.
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Affiliation(s)
- Tongyu C Wikramanayake
- Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, U.S.A.,Molecular Cell and Developmental Biology Program, University of Miami Miller School of Medicine, Miami, FL, U.S.A
| | - Jérémy Chéret
- Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, U.S.A
| | - Alec Sevilla
- Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, U.S.A
| | - Mark Birch-Machin
- Dermatological Sciences, Translational and Clinical Research Institute, and The UK National Innovation Centre for Ageing, Newcastle University, Newcastle upon Tyne, UK
| | - Ralf Paus
- Frost Department of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, U.S.A.,Monasterium Laboratory, Münster, Germany.,Centre for Dermatology Research, University of Manchester, and NIHR Manchester Biomedical Research Centre, Manchester, UK
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